Telegraphy.



No. 707,829. Patented Aug. .26, I902.

A. C. CREHURE.

TELEGRAPHY. A licmbn filed Oct. 2'1, 1901.)

5 Sheets SheBt I.

(No Model.)

ATTORNEY Patehted Aug. 26, I902.

A. C. CREHORE.

' 5 Sheets-Sheet 3.

(m3 Model.)

lNVENTOR (NoModeL) Paiente'd Aug. 26, I902. A. c. GREHORE.

TELEGBAPHY.

(Application filed Oct. 21, 1901.)

Sheets-$heet 4.

Patented Aug. 26, .l902. A. C. CREHURE.

I No. 707,829.

TELEGRAPHY.

(Application filed Oct. 21, 1901.

5 Sheets-Sheet 5.

(No Model.)

awvguboz witnesses QZT A42 6141mm;

NORRIS PETERS 00.. PHOTO-LUNG. wmnma'ron, u, e.

rrnn STATES PATENT OF ICE.

ALBERT O. CREl-IORE, OF TARRYTOVVN, NEW YORK.

TELE G RAPHY.

SPECIFICATION forming part of Letters Patent No. 707,829, dated August26, 1902. Application filed October 21,1901. Serial No. 79,383. (Nomodel.)

To a, whom it may concern:

' Be it known that 1, ALBERT O. Cannons, a citizen of the United States,and a resident of Tarrytown, in the county of Westchester and State ofNew York, have invented certain new and useful Improvements inTelegraphy, of which the following is a specification.

My invention relates to that class of telegraphs known assuperposed-current telegraphs, wherein two messages may be sentsimultaneously over the same line or circuit, one by the use ofmomentary currents, or on rrents of short duration sharply defined orhaving a high rate of change of electromotive force, and the other bycurrents having a lower rate of change and, generally speaking, oflonger duration and upon which the momentary currents are superposed.

In the following description the momentary currents will be referred toas pulsatory currents, and the currents of longer duration will bereferred to as continuous currents.

As my invention is particularly useful when the continuous currents areused in the manner in which they are employed in the ordinary Morsetelegraph, I will describe and show my invention as carried out inconnection with a Morse telegraph-line.

\Vhile I describe my invention as carried out in connection with thosesuperposed-current systems wherein the signals on the pulsatory-currentside are transmitted by using for each signal a succession of pulsatorycurrents and determining the length of time during which pulsatorycurrents shall be permitted to flow uninterruptedly, it is also usefulfor those systems wherein two pulsations only are used for eachsignal,.one marking the beginning and the other the end of the signal-orcharacter. 'It will also be obvious that on the pulsatory-current sideof the system spaces might be made by permitting the pulsatory currentsto flow and the signals be made by interruptions in the continuity offlow for greater or less periods of time.

My invention relates mainly to the transmitting portion of the system;and its object is to reduce the impedance to the flow of the pulsatorycurrents as well as of the continuons currents in a superposed-currentsystem of telegra'phy, thus permitting the system to be worked through alarge number of waystations, and also to secure other advantages moreparticularly hereinafter described.

The invention consists, broadly, of a novel system ofsuperposed-currenttelegraphy for way-station work in which means areprovided whereby the impedance of any inductance or condenser employedin transmitting over either side of the system may be removed from thecircuit when the transmittin g-key orother appliance is not in use,leaving only the impedance of any reactance or condenser at each stationnecessary for use in receiving on either side of the system. By thismeans the total normal impedance is greatly reduced, and the greatestincrease at any time is that required for the two simultaneoustransmissions, so that it is possible by my system to operate aWay-station circuit with a very much larger number of stations than hasheretofore been practicable.

My invention relates also, among other things, to the manner ofarranging the transmitters for the continuous and pulsatory currentsides of the system upon the circuit with relation totheir receivers;and it consists, substantially, in placing said transmitters in branchesaround acondenser and an inductance,respectivel y, which branches areentirely independent of those branches or portions of the circuit inwhich the receivers for the continuous and pulsatory current sides ofthe system are located. The object of this part of my invention is toeliminate practically all disturbance of the receivers from theoperation of the transmitters. This part of my invention may be usedwith any arrangement of receivers, although I prefer to employ thatarrangement in which they are in shunt to one another and are providedwith a third branch,which containsanon-inductive shunting-resistance, ashereinafter more particularly described.

My invention consists, further, in an approved arrangement oftransmitters for the continuous and pulsatory current sidesof the systemwith relation to one another and it consists,substantially,in placing orlocating them in shunt relation to one another, the shunt containing thecontinuous-current transmitter being provided with an inductance andthat containing the pulsatory-current transmitter being provided with acondenser.

While my invention has a large field of utility in a system wherein thesignals sent on the pulsatory side of the system are sent without apulsatory-current generator at said station, it is also useful insystems in which a generator is used in connection with the key orstation from which signals are to be sent by the pulsatory-current sideof the system.

As hereinafter described, the transmitter for the pulsatory-current sidemay be a device like a Morse key adapted to simply make and break thecondenser-shunt, and the pulsatory-current generator may be then locatedat another station, or the transmitter may be a device adapted tointroduce into or remove from the shunt a pulsatory electromotive forceoriginating at its station, as would be accomplished by the use of acontinuity-preserving key and pulsating generator or by including thesecondary of a transformer in the shunt and using a key to make andbreak the circuit of a generatorincluded in the primary circuit of saidtransformer.

In the subjoined description and claims, therefore, the term transmittershould be understood as including any of the arrangements above referredto or their equivalents.

Another feature of my invention relates to the means forshort-circuiting the reactance and condenser when the two transmittersare in a special relation to one anotherviz., a shunt relation; and itconsists, substantially, of two interdependent switches so arranged andcooperating that neithercan complete the short circuit around theapparatus unless the other is in position to close circuit.

My invention relates, further, to the relative arrangement of the twotransmitters, each in its shunt or branch, as respects the condenser andreactance whereby the shortcircuiting devices employed forshort-circuiting the transmitting apparatus when not in use may besimplified; and it consists. substantially, in placing the transmittersat opposite ends, respectively, of the branches containing the condenserand inductance.

The invention consists also in the combinations of apparatus and detailsof construction hereinafterdescribed and then specified in the claims.

In conjunction with the arrangement of transmitting devices hereindescribed and claimed any desired arrangement of receiving apparatusupon the circuit may be employed. It is preferable to arrange saidreceiving apparatus, however, in branches or portions of the circuitindependent of those containing the transmitters, and I also prefer toemploy, in conjunction with the hereinclaimed arrangement oftransmitters, that arrangement of receivers which is more particularlydescribed and claimed in another application for patent filed by me andwhich involves the placing of said receivers in shunt the continuous-current receiver.

In the accompanying drawings, Figure 1 is a general diagram of circuitsand apparatus for a way-station system equipped according to one way ofcarrying out my invention. Fig. 2 is a diagram of a system substantiallythe same as Fig. 1, excepting that some of the Way-stations havecontinuous-current apparatus only and that the stations havingpulsatory-current apparatus are provided with a pulsatory-currentgenerator, whereas in Fig. l the pulsatory-current generator is at aterminal or another station and is continually furnishing pulsations tothe circuit while transmission is going on. Fig. 3 shows the arrangementof Fig. 1 as it practically exists when two stations are transmittingsimultaneouslyone by the continuous-current side of the system and theother by the pulsating-current side-parts which are short-circuitedand-which do not, therefore, offer any impedance being omitted from thediagram. Fig. 4 shows, diagrammatically, the actual condition of thesystem, Fig. 2, as to impedance while transmission is going on over bothsides of the system. Fig. 5 illustrates a modified arrangement of thetransmitting apparatus that might be used with the same arrangement ofreceiving apparatus as is shown in Fig. 2 at stations A U IV or withother arrangements, assuming that the transmission is to be effected bya pnlsatory generator continually connected to the circuit duringtransmission on the pulsatory-current or No. 1 side. Fig. 6 showsanother arrangement of the receiving apparatus that might be used withthe arrangement of transmitting apparatus shown in Fig. 1, the receivingapparatus being in the relation to the circuitwhich it assumes when theswitches of a way-station are thrown to position for transmitting. Fig.7 shows the relation of said receiving apparatus to the circuit when thetransmitting devices are not in use and the receiving apparatus is readyto receive a message. Fig. 8 shows a form of switching apparatus bywhich this'rearrangement and removal of impedance used in transmittingmay be effected. Fig. 9 shows another arrangement of transmittingapparatus for the pulsating-current side of the system. Fig. 10 shows inplan an attachment that may be made to an ordinary Morse key to adaptits circuit-closer to use in my system without reconstruction of theMorse key. Fig. 11 is a plan of the key with the attachment in place.

Referring to-Fig. 1, 6 indicates the pulsatory-current generatoremployed in sending signals by the pulsatory-current side of the system.Said generator is preferably an alternating-current dynamo adapted togenerate a sine-wave or approximately a sine-wave eleotromotive force,and the generator-coils of the machine may be connected directly to IIGthe circuit, or, as well understood in the art, they may supply anelectromotive force to the circuit inductively through the interventionof a transformer whose secondary is in the line-circuit, while themachine-circuit includes the primary of the transformer. Thecontinuous-current generators, which might be dynamomachines, areindicated by the numeral 5. One of these may be used at each end of theline or section of line to keep the line charged with continuouscurrent, said generators being connected so that their polarities shallconspire. A pulsatory-current generator 6 is shown at each end of theline, which line, as indicated, has two terminal stations A W. Inpractice only one of the generators 6 would be used at one time. Thegenerator at A is shown connected into the line in circuit with thecontinuous-current generator, while thatatstation Wis showndisconnected. The switching appliances 2a, whereby this may be done, maybe of the typical form indicated. The generator 5 at the same stationwith the pulsating-current generator may be removed from the circuit bya switch 25. It will be understood, however, that the present inventionis not confined to any particular location of the generators upon thecircuit. The continuous-current transmitters, which may be ordinaryMorse keys, are in each case marked 1, and the pulsatory-currenttransmitters, which may in each case also be Morse keys, are in eachcase marked 2.' In Fig. 1 I show two terminal and four way stations; buta larger number of way-stations may be employed, and, in fact, with thearrangement shown I have operated successfully over a circuit having asmany as twenty way-stations.

The line-circnitin the arrangement of transmitters shown in Fig. 1 isbranched through said transmitters, so that they are in shunt relationto one another. In the shunt to the transmitter 2 which operates on thepulsatory-current side of the system is a suitable inductance 12,usually of considerable reactance and through which the continuouscurrent may flow freely when the key 1 is closed in the operation ofsending signals on the continuous-current side. The reactance orimpedance of the coil 12, which is preferably of theclosed-magnetic-circuit type,obstructs the flow of the pulsatingcurrents, so that whenever the key 2 is opened in the process of sendinga signal the coil 12 acts practically to open the circuit to the flow ofthe pulsatory current. The closure of the key2 completes the shunt orbranch around said coil 12, said shunt or branch being of such characteras to permit the pulsatory current to flow freely. In the shunt orbranch with the key 2 is a condenser 8, which operates in conjunctionwith the key 1 in the opposite shunt or branch during the process ofsending signals on the continuous-current side of the system. While itopens the circuit or branch to the flow of the continuous currents, itdoes not prevent the pulsatory current from flowing. The key 1 operateson the continuous-current side of the system by simply making andbreaking a shunt around said condenser, each opening of theshunt-circuit by the key 1 acting practically to open the circuit to theflow of the continuous currents, because when it is,

opened the only path for such currents is through the condenser. Incases where the circuit is short or the number of stations equipped withcontinuous-current apparatus is small the operation of the key 2, if thesame were connected to a direct shunt across the terminals of theinductance12, might by shunting the resistance 12 produce a false signalin the continuous-current receivers of the system. The condenser 8,while operatin g in connection with the transmitter 1 in the manneralready described, has also the function of preventingsucli disturbanceupon the continuous-current side of the system through Variations ofimpedanceintroduced by the action of the key 2, since said condenser atall times keeps the shunt open to the flow of the continuous current,and the shunting of the reactance by key 2 Will not, therefore, shuntthe continuous current from the coil of 12. In a similar way if the key1 were arranged to close its branch or shunt around the condenserdirectly without any reactance being included in the circuit of 1 it isobvious that the operation of the key 1 would under the conditions abovesupposed produce changes of impedance upon the pulsatory-current side ofthe system which might give rise to disturbance in the action of thepulsatory-current receivers. Such disturbance is, however, prevented bythe presence of the inductance 12 at the time the key 1 is closed tosend a signal by the continuous-current side. Inasmuch as the inductance12 forms an obstacle to the flow of the pulsatory currents,pulsatory-current signals are not transmitted by the operation of thekey 1. Hence it will be seen that by the arrangement of the keys inshunt to one another, one shunt containing the reactance and the otherthe condenser, each key may operate in the intended manner, one to forma shunt around a reactance, which shunt will permit the pulsatorycurrents to flow, and the other to close a shunt around a condenser,which will permit the continuous current to flow, while neither key willproduce a disturbance upon that side of the system with which theopposite key is designed to work.

In the ordinary operation of the Morse keys it is usual to switch thekey out of circuit when not in use by a supplemental switch-lever orcircuit-closer upon the keybase, as well understood in the art. Such acircuit-closer is indicated by the numeral 15 and operates in each caseto shunt the key 1 or 2 by completing the connection from the lever tothe contact connected with the front post or anvil. The use of such alever on each key without additional provision would &

obviously, however, not short-circuit the re actance 12 or the condenser8 when, one or both keys are out of use, whether one or both switches beclosed. It is also obvious that even if the key 1 be out of use thereactance 12 should maintain its relation to the circuit in order topermit the key 2 to send its signals, and, conversely, even if the key 2be out of use the condenser should maintain its relation to the circuitif the key 1 be still in use. If both keys be out of use, however, it isdesirable that the inductance and the condenser be both removed from thecircuit in order to reduce the resistance of the line. To accomplishthis result simply and Without requiring anyspecial construction ofthetele-' graph-keys, I may arrange the said keys as shown at opposite end,respectively, of the branches in which they are included and provide thecircuit-closer 15 with a supplemental contact 16. The supplementalcontacts 16 being interconnected, as shown, it is possible for eitheroperator to use his key and switch 15 in the ordinary way and toaccomplish the following results: When both switches'are open, the twokeys 1 and 2 may be used simultaneously,and each operator may send hismessage over the circuit in a well-understood way one by the pulsatorycurrents and the other by the continuous currentswithout interferingwith one another. When the operator using key 1 finishes sending, hethrows his switch 15' just as he would on any ordinary Morse circuit,thereby short-circniting his key and completing a connection fromcontact 16 to the contact 16 of the key 2. Inasmuch, however, as theswitch 15 for key 2 is still open, no eifect is produced by the closureof the switch 15 for key 1 beyond the mere short-circuiting of thecontacts of the key, and the reactancecoil 12 still remains in thecircuitas an obstruction to the flow of the pulsatory currents, so thatkey 2 will continue to act in its intended manner. As soon as, however,the operator using key 2 finishes transmitting the mes sage he simplycloses his switch 15 in the ordinary way to short-circuit his key, andthereby at the same time completes the connection on the contact 16, sothat there is now formed a short-circuit from oneside of thestationdirectly to the other, avoiding both the reactance-coil and thecondenser. Conversely it will be seen that if both keys be in use andthe use of key 2 ceases first and its switch be then closed theoperation of key 1 in shunting the condenser 8 will not be interferedwith, but that as soon as the switch 15 of the key 1 is closed both thereactance-coil and the condenser Will be short-circuited. It will alsobe seen that either key may be brought into use by simply opening itsappropriate switch, which will have the effect of breaking the shunt forthe key itself and alsoof breaking the short circuit for both thereactance-coil and the condenser, the connection of both of which in thecircuit is necessary for the proper operation of either key.

The arrangement of the transmitters with the inductance and condenser inshunt relation to one another and also the arrangement ofshort-circuiting switches is useful with any arrangement of thereceiving apparatus. I have shown it in Fig. 1 as employed upon acircuit on which the receivers are arranged in the manner described andclaimed in another application for patent by me filed of even dateherewith, Serial No. 79,385. In this arrangement the continuous-currentreceiver or relay 3 is in shunt to the pulsatorycurrent receiver4 andcondenser 8. The reactance or inductance of the relay 3 forces thepnlsatory currents into the shunt or branch containing thepulsatory-current receiver, in which branch it may flow through saidreceiverand condenser. The condenser, on the other hand, forms a bar tothe free flow of the continuous current and forces the same to take thepath through the receiver 3 whenever said continuous current ispermitted to flow over the circuit by the operation of a key 1, which,as already explained, closes the shunt around a condenser.

9 indicates a suitable non-inductive resistance placed in shunt to thereceiver 3 to di vert the discharge of the condenser 8 and prevent kicksin said receiver. It also operates to protect said receiver from thedisturbing action of any other transitory or va-' riable current comingfrom condensers, inductances, or other sources outside of the receiverbranches by affording a shunt path or path of comparatively lowresistance for them. It also has the function of diminishing theresistance of the station apparatus to the flow of pulsatory currentsand permits the pulsatory current to flow down the line more freely tostations more distant from said generator, as set forth in myapplication for patent of even date herewith, Serial No. 79,385, inwhich this device is specifically claimed, together with the arrangementof receivers.

It will be noticed that the transmitters 1 are not in the shunt with thereceivers 3, but are at points on the circuit outside said shunt, sothat the instruments are less liable to disturbance upon the operationof the key and the discharge of the condenser in the shunt around it;also, the transmitter 2 for the pulsatory-current side of the system isin a shunt or branch independent of the branches containing thereceiving instruments and for a similar purpose. This arrangement is ofgreat practicalimportance, as it substantially eliminates thedifliculties and disturbances in the action of the relays which wouldarise from the operation of the transmitters if the attempt be made tolocate and operate them in the same branches with their receivers,respectively.

The diagram Fig. 1 shows a line having two terminal and four waystations. The terminal stations are marked A and W and the severalintermediate stations are marked B,

IIO

wasze C, U, and V. A larger number of intermediate stations might beemployed. Upon examination of the diagram it will be seen that theswitch 15 for the continuous-current side of the system at station V isopened and the switch 15 for the pulsatory-current side of the system atstation A is also opened. At all other stations the switches 15 for bothkeys 1 2 are closed, and the impedance at} forded by the inductance 12and condenser used in connection with the transmitters is removed fromthe circuit at said stations. The receivers 8 and 4-, however, maintaintheir relation to the circuit and each will respond to its own propercharacter of current. The pulsatory currents controlled by thetransmitter 2 at station A iiow over the whole circuit and operate allof the receivers 4 on the circuit, including that at station V, theaction of the key being simply to open and close the shunt around theinductance 12 at station A and each closure allowing the pulsatorycurrents to flow freely over the circuit without encountering theimpedance offered by the inductance 12. Said pulsatory currents flowingdown the line operate upon all the receivers 4, even to the mostdistant. Similarly any key 2 at any station may be employed intransmitting the signals by the pulsatory-current side of the systems tostations farther down the line or toward station N. The operation of thekey 1 at station V produces the usual effect of the Morse key on thecontinuous-current circuit, and all the instruments 3 on the circuitshown will respond in obvious manner. The actual condition of thecircuit as to impedance, &7C., under the condition assumed for theswitches or circuit-closers can be more readily seen in the simplifieddiagram, Fig. 3. As will be seen, neither the inductance nor thecondenser used in transmitting is in operative relation to the circuitat any station except at those engaged in transmitting, and theimpedance offered by the same to the flow of the pulsating currents istherefore eliminated at stations B G U W and all others in the circuitexcepting A and V. \Vith a line having a large number of stationsequipped as shown it may not be found expedient to transmit from station1V toward station A through any large number of stations by the use ofthepulsatorycurrentsgenerated at A. Under such circumstances and if itis desired to reach as far as station A by the pulsatorycurrent side ofthe system the operator at WV who Wishes to use the pulsatory-currentside mayinstruct station A on the con tin uou s-cu rrent side of thesystem to remove the generator 6 from connection with the line atstation A, and the operator at may then switch in his generator 6 and byoperating his key 2 will cause the pulsatory-current receivers at allthe stations on the whole circuit to respond, inasmuch as the flow ofcurrents from said generator is completely cutoff by the action of saidkey. Also, as will be obvious,

the operator at any intermediate station be tween W and A may transmitover the pulsatory-current side of the system efiectually to allstations in the direction of station A in a similar way, the generator 6having been connected at station W and that of A. having been removed.If the station is near W, the operator may also transmit to W andintermediate stations between his own station and W by modifying thepulsatory current of generator 6 at station W through opening andclosing the shunt around the inductance 12, as already explained.

I do not limit myself to placing the pulsatory-current generatoratterminal stations on the circuit, as it may be placed at other pointsthereof and the flow of its current modified in the manner alreadydescribed by the action of the key 2.

While I have shown all of the stations similarly equipped in the diagramFig. 1, some intermediate stations might be provided with apparatusdesigned to work only on the continuous-current side of the system, asindicated at station 0 in Fig. 2 of the accompany- .ing drawings.

In the diagram Fig. 2 I have shown two terminal stations A W and oneintermediate station U, all provided with apparatus for telegraphingboth by continuous and pulsating current. At the terminal-stations thetransmitting apparatus for the pnlsatory-cur rent side of the system maybe of any desired form, but is shown as comprising a key 2, controllingthe local circuit of a magnet which operates upon a transmitter 2' ofthe continuity-preserving type and having its contacts connected, asshown, to the condenser in the shunt around the key 1 and to thepulsating generator 6 in such manner that when the transmitter is openedthe branch containing the condenser is closed directly to thecontinuation of the circuit leading to the generator 5 and earth. Whenthe key is closed, the direct connection is broken and the generator 6is included in the branch with the condenser, so that the pulsatory current generated thereby will be caused to flow upon the circuit and opeate upon the receivers for the pulsatory-current side of the system. Thetransmitter 1 for the continuous side of the system is in the branchwith the reactance 12, which latter operates to prevent the pulsatingcurrents in the generator 6 from flowing in short circuit when s tidgenerator is connected into the condenser branch. The transmittingapparatus at station U is of similar character, so that when the transmitter 2 is on its back stop the short circuit through the condenserwill be closed directly,

but when on its front stop the direct connection formed over the backcontact will be broken and a substitute connection throughsatory-current receivers 4 on the circuit. A similar arrangement ofdevices to that shown in Fig. 1 may be employed for cutting out theimpedance of the condenser and inductance used in connection with thetransmitting apparatus at the stations A U W or any stations similarlyequipped. The circuit closing switches 15, bywhich this is effected, areshown'as used in connection with the transmitter 1 and with thekey2,which controls the transmitter 2, and are connected in a similarway to those shown in the diagram Fig. 1. Upon the closure of bothcircuit-closers a shunt which short-circuits both the reactance 12 andthe condenser 8 is formed over the contacts 16 of the circ nit-closers.Other way-stations upon the circuit, Fig. 2, may obviously be providedwith continuous-current apparatusas, for instance, stations B, O, and V.In each of these cases an artificial shunt containing a condenser 8 andan ind uctance 12 is pro vided, said inductance taking the place of theinductance alforded by the receiver 4 at stations A U W and otherssimilarly equipped.

The inductance 12 should be adjusted so as to balance by its reactancethe opposing reactance of the condenser, and to thereby furnish at thestations B O V a ready path through said stations for the pulsatorycurrents at all times. This inductance 12, as described in anotherapplication for patent filed by me of even dateherewith,SerialNo.79,387,whereinI claim the balancing of the condensercapacity or reactance by the reactance, both arranged in the shunt t0the continuous-current receiver 3, preferably consists of a coil woundupon a core which has a magnetic circuit of iron, completely closedexcepting at one or more points, where a narrow or thin break isafforded by an air-gap or similar break in the magnetic continuity ofthe iron circuit. Said inductance might, however, be of other form. Thetransmitter l at each of the waystations operates to break and close thecircuit for the continuous currents, while the shunt containing thecondenser 8 afiords at all times a path for the pulsatory current.

, The non-inductive shunt 9 at said stations B O V has the functionalready described. Assuming that transmitter 1 at station B is in useand transmitter 2 at station U, the condition of the circuit at variousstations as to the interposition of condensers and inductances used intransmitting would be as shown in skeleton in Fig. 4.

In the modified arrangement of the transmitter illustrated in Fig. 5 thetransmitters 1 and 2 are arranged in shunt, respectively,

' to a condenser and to a reactance, but in series instead of shuntrelation to one another, These shunts or branches, however, for saidtransmitters are, as in the previous figures, branches which areindependent of those parts of the circuit in which the receivers arelocated. The receivers may be arranged in any desired relation to thecircuit, but preferably in the relation already described. In

the pair of contact-levers 30.

circuit with the condenser 8, to which the transmitter 1 forms a shunt,a coil may be placed for the purpose of preventing sparking at thecontacts of the key. This coil is preferably an inductance-coil and isalso preferably adjusted to balance by its reactance the reactance ofthe condenser 8, and thereby permit pulsatory current to flow morefreely to said branch or shunt. For a reactance used in this relation Iprefer to employ the form 12, such as already described and which isclaimed in another application for patent filed by me of even dateherewith, Serial No. 79,387. Each key 1 and 2, Fig. 5, is provided witha circuit-closer 15 of any desired character. As will be seen in thisarrangement, as in the other already described, both the inductance andthe condenser used with the transmitting apparatus for both sides of thesystem may be shunted out of the circuit when the transmitters are notin use. In Fig. 6 the shunt arrangement of the transmitters is shown,together with a modified arrangement of the receivers. The receiver 3for the continuous-current side of the system has the shunt 9 alreadydescribed, and the receiver 4 is in shunt to an inductance or reactance12, operating after the manner ofa transformer having a single coil toset up currents in the receiver branch. The varrangement of receivers asshown in Fig. 6 would not be permissible for a very large number ofWay-stations because of the high impedance that would be afforded to thecurrents flowing over the line, although under some circumstances itmight be permissible when the apparatus at a station is in use fortransmitting, provided that at all other stations where the transmittersare not in use provision be made for combining said receivers with oneanother and with a condenserin the manner already described, or, inother words, in substantially the relation indicated in Fig. 7. For thecondenser used in this relation the condenser 8 used with the transmit--ters might be employed by making use of proper switchingappliances-such, for instance, as indicated in Fig. 8the action of whichwould be not only to rearrange the receivers with the condenser 8, butto shunt the inductance 12 in the transmitter branch with it entirelyout of the circuit. As a switching appliance for this purpose aninstrument like an ordinary pole-changing instrument might be used, butwith two contacts insulated from one another instead of a common contactfor The levers 30 of the pole -changer being connected, re spectively,to the line theinsulated contacts 31 would be connected, as shown, toone terminal of the receivers 3 and 4, while the contact-lever 33, whichis placed between levers 30, would be connected to an opposite terminalof the receiver 3. Connection with the condenser 8 and the oppositeterminal of receiver 4 would be made from one of the levers 30, asindicated. The circuit-closers 15 IIO for the two transmitters 1 and 2would control the local circuit of the operating-magnet 34E, which actson lever 33. When both circuit-closers 15 are in closed position, theycomplete, by the supplemental contact 1 '6, already described, the localcircuit of magnet 3st, as may be traced in the diagram, thereby holdingthe parts in the relation shown, so that if circuit be traced from onebar or lever 30 to the other it will be found that the receivers andcondenserare in the circuit relation indicated in Fig. 7. The opening ofeither circuit-closer 15 causes the lever 33 to reverse its position andto reverse the connections of levers 30 and contacts 31, so that thecondenser 8 will be brought back to a shunt relation to the transmitter1 and the reactance 12, which had previously been out of circuit, willbe brought in shunt relation to the transmitter 2, while the receiverswill be placed in circuit in series relation to one another, as shown inFig. 6. This condition may be readily traced in the diagram Fig. 8 andwill result from the operation of either circuit-closer 15 when eitherkey 1 or 2 is to be employed for transmitting. By these devices, as bythose already described, the reactance of any condenser and inductanceemployed in transmitting is removed from the circuit when the apparatusat a way-station is out of use. Other arrangements of devices might beused for accomplishing the same or substantially the same results as areeffected by the particular arrangement illustrated in Fig. 8.

In Fig. 9 I show that modification of my invention which involves simplythe use of a transmitter for the pulsatory-cu rrent side consisting of atransformer, a pulsating generator, and a controlling-key, the lattertwo de vices being in the primary of the transformer, while thesecondary holds the same relation to the circuit as the generator 6 atstation U of Fig. 2. The circuit-closers 15 operate, like those alreadydescribed, to shunt the transmitting apparatus out of the circuit whenthey are both in closed position, and the opening of either throws theapparatus into condition for transmitting.

In order to permit ordinary Morse keys as at present in use to be usedfor the purposes of my invention, I propose to mount the supplementalcircuit-closing contact 16 upon a suitable base-plate 40, Fig. 10, whichis preferably of metal, and in that case has the spring forming thecontact 16 secured to a piece of insulation 41, that in turn is fastenedto the base-plate 40. The plate 40 is provided with openings 42, throughwhich the legs by which the ordinary Morse key is fastened to a table orbase may pass. That one of the openings 42 through which the legcorresponding to the front contact of the key passes is provided with aninsulating-bushing. To equip akey so that its circuit-closer 15, Fig.11, as at present employed may operate in conjunction with asupplemental contact 16 in the manner already explained, it is simplynecessary 'to place the attachment 4L0 beneath the base of the key, thekey having been first removed from its support and the plate 40, withits attached contact 16, put in position upon said support.

It will be seen that in using the Morse keys the operators of theinstrument and apparatus constructed and arranged in accordance with myinvention will use the circuitclosers 15 in just the same manner as theyemploy them upon ordinary Morse circuits, and hence no difficulties willbe encountered in equipping the circuit according to my i11- ventionbecause of the necessity of instructing the operators in any special useof the transmitting appliances. Moreover, the

Morse keys at present employed may be util ized by simply attaching thedevice shown in Fig. 10.

l/Vhat I claim as my invention is 1. In a superposed-current telegraph,the combination substantially as described with continuous and pulsatorycurrent receivers arranged in shunt relation to one another and having acondenser in the pulsatory-current branch, of transmitters for the twosides of the system arranged in shunt relation to one another, aninductance in the branch with the continuous-currenttransmitter,and acondenser in the branch with the pulsatory-current transmitter, saidtransmitter branches being independent of those containing thereceivers.

2. In a superposed-current telegraph, the combination of transmittersfor the pulsatory and continuous sides of the system respectively,arranged in shunt relation to one another, and an inductance in theshunt or branch containing the continuous current transmitter wherebywhen the latter transmitt-er is closed the transmitter in the otherbranch opens and closes a shunt around the branch which offers animpedance to the flow of the pulsatory current.

3. In a superposed-current telegraph, a sin gle main line havingtransmitting apparatus for the continuous and pulsatory sides of thesystem respectively, arranged in shunt relation to one another, incombination With an inductance in the shunt containing thecontinuous-current transmitter and a condenser in the shunt containingthe pulsatory-current transmitter.

4. In a superposed-current system of telegraphy, the combination withthe continuouscurrent and pulsatory-current transmitters at a station,of means for short-circuiting the transmitting apparatus for thepulsatory-current and continuous-current sides of the systemrespectively, said short-circ uiting devices being connected in seriesas described so that neither shall be effective to short-circuit untilboth are thrown to short-circuiting position.

5. In a superposed-current telegraph, the combination substantially asdescribed, of a continuous-cnrrent transmitter and a pulsatory-currenttransmitter placed in shunt relation to one another upon the samecircuit but both in series relation to the portion of circuit containingthe receivers said transmitter branches or shunts containingrespectively a condenser and an inductance as and for the purposedescribed.

6. In a superposed-current telegraph, two branches of the line-circuitin shunt relation to one another, one containing a Morse key andinductance, and the other a condenser and Morse key, said keys beingarranged at opposite ends of the branches respectively, withtheirshort-circuiting switches connected direct to line, andsupplemental contacts for said switches connected together as and forthe purpose described.

7. In a superposed-current telegraph, the combination substantially asdescribed of a transmitter for the continuous-current side of the systemand an inductance arranged in one shunt or branch of the circuit, atransmitter for the pulsatory-current side of the system and a condenserarranged in another branch which is in shunt relation to the firstnamedbranch said transmitters being placed at opposite ends of their shuntsor branches respectively, a switch for each transmitter whereby it maybe short-circuited without short-circuiting the reactance or condenseras the case may be, and supplemental contacts for said switchesconnected as described so that only when both switches are closed boththe inductance and condenser will be shortcircuited.

8. In a superposed-current system of telegraphy, the combinationsubstantially as described,with suitable continuous-current andpulsatory-current receivers, of continuouscurrent and pulsatory-currenttransmitters, a condenser in a shunt to a branch containing thecontinuous-current transmitter and an inductance in a shunt to thebranch containing the pulsatory-current transmitter, said transmitterbranches being independent of those branches or parts of the circuit inwhich the said receivers are located.

9. In a superposed-current telegraph, transmitters for thecontinuous-current and pulsatory-current sides of the systemrespectively, arranged in shunt relation to one another and each adaptedto make and break the shunt in which it is placed, in combination withan inductance in the shunt containing the continuous-current transmitterand a condenser in the'shunt containing the pulsatory-currenttransmitter.

10. In a superposed-current telegraph, the combination of apulsatory-current generator, a continuous-current generator,transmitting-keys adapted to make and break circuit and normallyshortcircuited, a condenser, a reactance and means for introducing thekeys into circuit, one in a condensershunt around the reactance and theother in a shunt around a condenser.

*11. In asuperposedcurrent system of telegraphy, the combination withway-station receiving apparatus comprising a continuouscurrent receiverin shunt to a condenser and the pulsatory current receiving apparatuswhile the apparatus is in the condition for receiving, of transmittersfor the two sides of the system both normally short-circuited, branchesor shunts of the circuit, one a condenser shunt or branch around areactance, and the other an inductance shunt or branch around acondenser, and means for including said transmitters respectively in thebranches.

12. The combination with the continuous and pulsatory currenttransmitters in shunt relation to one another, of a reactance, acondenser, and two interdependent circuit-closing devices, one for eachkey, cooperating as described to short-circuit the condenser andreactance.

13. In asuperposed-current system of telegraphy, the combination withtwo branches of the circuit one containing an inductance andtransmitter, and the other containing a condenser and transmitter, of ashort-circuiting device for each branch, one adapted to shunt theinductance and the other to shunt the condenser saidshort-circuitingdevices being connected in series as described.

14. In asuperposed-current system of telegraphy, two branches ofline-circuit in shunt relation to one another, one containing aninductance and Morse key, the other a condenser and Morse key combinedwith keyswitches having supplemental contacts, and a connection betweensaid contacts forming a short circuit for both the inductance and thecondenser, as and for the purpose described.

15. In a superposed-current telegraph, the combination of transmittingapparatus for the pulsatory-current side of the system, aninductance-shunt therefor, transmitting apparatus for thecontinuous-current side of the system, a condenser-shunt therefor andcircuit-closing devices for said transmitting apparatus adapted to forma short circuit around both the inductance and the condenser when saidtransmitting apparatus is out of use.

16. In a superposed-current telegraph, the combination of acontinuous-current receiver, a pulsatory-current receiver, a condenser,an inductance, continuous-current transmitting apparatus in a branch ofthe circuit inde pendent of the continuous-current receiver and forminga shunt to the condenser,'pul- 'satory-current-transmitting apparatus ina branch of the circuit independent of the pulsatory-current receiverand forming a shunt to the inductance, and circuit-closing devicesadapted to short-circuit both said inductance and condenser when eithertransmitting apparatus is not in use.

17. In a superposed-current telegraph, the combination of aninductance,a pulsatorycurrent transmitter adapted to transmit signals byopening and closing a branch of the IIO main line around saidinductance, a condenser in the branch with the pulsatory-currenttransmitter, a continuous-current transmitter adapted to open and closea branch of the main line around said condenser, and circuit-closingdevices for sh unting' either the condenser or inductance out of theline-circuit when either transmitter is not in use.

18. In a superposed-current telegraph, the combination with apulsatory-current generator and a Morse key controlling the connectionof said generator with the line of a circuit-closer for said key,and acontact therefor connected to a branch leading from the key to the linearound the coils of said generator. 19. In a superposed-currenttelegraph, the

ALBERT O. CREIIORE.

Witnesses:

J. GALLWITZ, E. L. LAWLER.

